Testosterone, which is a male hormone responsible for secondary sex characteristics, belongs to the androgen group of steroid hormones, and is secreted primarily from sex glands. With respect to the male menopause, testosterone is associated with: (1) reduced sex desire, erectile capacity, and frequency; (2) reduced intellectual activity, cognitive functions, and spatial skills, and changes in mood, such as fatigue, feeling low, and anxiety; (3) sleep disorder; (4) reduced body fat mass, in association with reduced muscle mass and muscle strength; (5) increased visceral fat; (6) reduced body hair and skin diseases; and (7) osteopenia and increased fracture risk due to reduced bone density.
The quantity of testosterone existing mainly in the blood is analyzed for diagnosis. The increased testosterone is associated with androgen resistance, ovarian cancer, testicular cancer, congenital adrenal hyperplasia, or precocious puberty, and the reduced testosterone is associated with chronic diseases, abnormal pituitary gland, delayed puberty, abnormal testicles, or noncancerous tumors composed of pituitary gland cells overproducing prolactin.
The testosterone existing in the body is not in a free state: most of the testosterone is in a state of being bound to protein. That is, only about 2-3% of testosterone is in a free state, and 44-65% of testosterone exists in a state of being bound to sex hormone binding globulin (SHBG) and 33-54% of testosterone exists in a state of being bound to albumin. Due to these facts, the testosterone in the blood is difficult to detect.
In order to remove proteins binding to testosterone, it is necessary to use an acid solution causing protein denaturation or 2-methoxyestradiol (2-ME), which is a hormone having a similar structure to testosterone. In some cases, the reaction conditions and the reaction reagents can be controlled in order to obtain a free state of testosterone obtaining sufficient signals.
When a hormone, such as testosterone (molecular weight: 288.42), is applied to a conventional detection method, the small molecular weight thereof makes it impossible to use a sandwich assay.
The detection method of the present invention uses a competitive assay, and thus, the present invention is to establish a method capable of detecting small molecules, such as testosterone, more accurately, by using gold nanoparticles as a medium to amplify measurement signals with response sensitivity increased compared with a conventional assay using competitive reaction.
Throughout the entire specification, many papers and patent documents are referenced and their citations are represented. The disclosure of the cited papers and patent documents are entirely incorporated by reference into the present specification, and the level of the technical field within which the present invention falls and the details of the present invention are explained more clearly.